Bending machine



April 29, 1969 R. F. GIORDANO 3,440,847

BENDING MACHINE I Filed Oct. 13, 1965 Sheet of s April 1969 R. F. GIORDANO 3,440,841

BENDING MACHINE Sheet Filed Oct. 15, 1965 J". six fer" I April 9, 1969 R. F. GIORDANO 3,440,847

BENDING MACHINE Filed Oct. 15, 1965 Sheet 5 of a I L bra-24: A U

United States Patent 3,440,847 BENDING MACHINE Roger Francois Giordano, Deuil-la-Barre, France, assignor 50 Int. Cl. B21b 37/00; liZlj 7/02; 330]) 15/00 US. Cl. 72-12 18 Claims ABSTRACT OF THE DISCLOSURE A sheet metal bending machine wherein the recess of the air-forming die is flanked by a pair of deforming edges and wherein the punch has a centrally located ridge disposed between two stops which are separated therefrom by depressions serving to accomodate portions of the panels of a sheet which is placed between the die and the punch and is deformed around the ridge when the latter is caused to penetrate into the recess. Each panel of the thus deformed sheet is then engaged by one of the deforming edges and by one of the stops whereby the edges effect elastic deformation of the respective panels to compensate for differences in thickness or mechanical characteristics of successively treated sheets.

The present invention relates to bending machines in general, and more particularly to an improved bending machine for sheet metal. Still more particularly, the invention relates to a bending machine for sheet metal which utilizes a so-called acute-angle or air-forming die.

Bending dies for sheet metal are of the air-forming or of the full stamp forming type. When a bending machine uses a conventional air-forming die, the quality of the fold or bend depends on the cold rolling and on thickness of the blank. It happens quiet frequently that the same shipment of blanks contains blanks of different thicknessses. In such instances, a machine which uses a conventional air-forming die and a conventional counterdie will produce folds or bonds of different shape. As a rule, the quality of folds which are obtained by full stamp folding is much higher, but a serious drawback of such methods is that they require bending or folding forces which are three to five times higher than the forces required for air forming.

Accordingly, it is an important object of the present invention to provide a novel bending machine for sheet metal blanks or the like and to construct the machine for operation in accordance with the air folding method without, however, exhibiting the drawbacks of conventional machines which operate on the same principle.

Another object of the invention is to provide a bending machine of the just outlined characteristics which is capable of forming identical folds in any desired number of consecutively treated blanks, even if the thickness and/ or certain other characteristics of such blanck vary within a wide range.

A further object of the invention is to provide a bending machine which is used for carrying out an improved air forming method and which may be repidly and conveniently converted to form different types of folds.

A concomitant object of the invention is to provide a bending machine wherein the bending stresses are relieved or terminated in a fully automatic way as soon as the deformation of a blank reaches a desired degree and wherein the blank itself can trigger such relaxation or termination of bending stresses.

An additional object of the instant invention is to provide a novel air-forming die and a novel counterdie or 3,440,847 Patented Apr. 29, 1969 punch which may be used in an apparatus of the above outlined characteristics.

A further object of the present invention is to provide a novel method of bending metallic sheets and similar planar workpieces.

Another object of the invention is to provide a bending machine which operates in accordance with the air forming method but can bend metallic sheets with an accuracy which at least equals or even evceeds the accuracy of machines operating in accordance with the full stamp folding method, whose power requirements are only a fraction of power requirements of a machine which is operated in accordance with the full stamp folding method, and whose accuracy is not dependent on the skill or alertness of the operating personnel.

Briefly stated, one feature of my invention resides in the provision of a bending machine for sheet metal. The machine comprises an air-forming die member having a face provided with a recess bounded by two deforming edge portions, and a punch member having a ridge disposed between the two deforming portions and a pair of stops spaced from the ridge. Each of the two deforming portions is located between the ridge and one of the stops so that, when a sheet metal blank is placed onto the face of the die member and the ridge is caused to penetrate into the recess, the blank is bent around the ridge and forms a pair of mutually inclined panels each of which abuts against one of the deforming portions and against the respective stop. The deforming portions and the stops are preferably disposed in mirror symmetry with reference to a plane which extends lengthwise of and halves the recess and the ridge.

In accordance with another important feature of my invention, the machine preferably comprises drive means for moving one of the two members with reference to the other member to thereby move the ridge into or from the recess, and control means for regulating the operation of the drive means. The control means may include a signal generator which is provided on the punch member intermediate one of the stops and the ridge and is arranged to produce a signal which terminates the operation of the drive means in a direction to effect movement of the ridge into the recess when the respective panel of the blank assumes a predetermined position with reference to the control means. For example, the signal generator may constitute the movable member of a hydraulic or pneumatic valve which controls the operation of a fluid operated drive, and such movable member may be bodily displaced by one of the panels when the bending of the blank has reached a predetermined stage. Alternatively, the control means may comprise two signal generators each of which may constitute one terminal of a normally open electric switch. The switch is closed by the blank when the two terminals are contacted by the respective panels, and the switch then sends a signal which reverses the drive means so that the ridge of the punch member begins to move out of the recess in the die member.

It is also possible to construct at least one of the stops in such a way that it constitutes a signal generator and reverses the drive means when the respective panel assumes a predetermined position with reference to such stop.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved bending machine itself however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawings, in which:

FIG. 1 is a somewhat schematic fragmentary end elevational view of a punch member which forms part of a bending machine embodying one form of my invention;

FIG. 2 is a fragmentary end elevational view of a die member which cooperates with the punch member of FIG. 1;

FIG. 3 is an end elevational view of the members shown in FIGS. 1 and 2 and illustrates a sheet metal blank in the final stage of deformation;

FIG. 4 illustrates a portion of an electric circiut constituting a control unit for the drive which is used to move the punch member with reference to the die member and/ or vice versa;

FIG. 5 is a fragmentary end elevational view of a modified bending machine wherein the control unit for the drive comprises two movable valve members each of which may be bodily displaced by one panel of the blank;

FIG. 6 is a fragmentary end elevational view of a third bending machine wherein the control unit for the drive comprises two photoelectric cells;

FIG. 7 is a fragmentary end elevational view of a fourth bending machine wherein each stop on the punch member constitutes a signal generator; and

FIG. 8 is a fragmentary end elevational view of a greatly simplified fifth bending machine whereing the operation of drive for moving the ridge of the punch member into the recess of the die member need not be regulated by an automatic control unit.

Referring first to FIGS. 1-4, there is shown a bending machine which comprises a stationay air-forming die 10 having a top face 1012 which is provided with a V-shaped recess 10b bounded by two elongated parallel edge portions or deforming portions 11. The machine further comprises a counterdie 1 (hereinafter called punch) having a substantially wedge-shaped lower section 10 which terminates in an elongated ridge 2 located midway between the deforming portions 11. The radius of curvature of the rounded peripheral surface on the ridge 2 equals ar approximates the thickness of a sheet metal workpiece or blank 30 which is to be deformed in response to penetration of the ridge 2 into the recess 10b. The punch 1 further comprises two spaced parallel abutment portions 3 (hereinafter called stops) which are provided with sharp or rounded edges and are disposed outwardly of the deforming portions 11, i.e., each deforming portion 11 is located between the ridge 2 and one of the stops 3. The angle a indicates the mutual inclination of two panels 30a, and 30b which are obtained in response to bending of the blank 30 around the ridge 2 when the blank is placed onto the top face 10a and the section 1:: of the punch 1 is caused to penetrate into the recess 10b. The lines I indicate in FIG. 1 two planes which are tangential to the ridge 2 and extend into contact with the edges of the respective stops 3. These planes t make with each other the aforementioned angle a.

The wedge-shaped section 10 of the punch 1 is formed with a pair of depressions or channels 4 each of which extends between the ridge 2 and one of the stops 3. The purpose of the channels 4 is to accommodate two signal generators 5 forming part of a control circuit CU for a reversible drive D which serves to move the punch 1 with reference to the die 10. It is clear, however, that the punch 1 may be fixed to a stationary part of the bending machine and that the drive D may be used to reciprocate the die 10.

The signal generators 5 are mounted on the punch 1, preferably substantially midway between the ridge 2 and the respective stops 3, and are fully accommodated in the respective channels 4. Each thereof is electrically insulated from the metallic material of the punch 1 by a layer 6 of insulating material. These signal generators constitute the contacts or terminals of a normally open switch (see FIG. 4) which is installed in the control circuit CU of the drive D and is closed by the panels 30a, 30b when the blank 30 has undergone a desired deformation, i.e., when the panels 30a, 30b are flexed by the deforming portions 11 to such an extent that their median portions actually enter the respective channels 4 and come into bodily contact with the signal generators 5. The control circuit CU further comprises a master switch 40a which is closed prior to start of a bending operation and a relay 40 which is connected in series with the master switch 40a, with a source 40b of electrical energy, and with the switch which includes the signal generators 5. When the circuit CU is completed by the panels 30a, 30b of a properly deformed blank 30, the relay 40 is energized and opens a relay switch 41 which must be closed if the drive D is to operate in such a direction that the ridge 2 of the punch 1 penetrates into the recess 10b. The relay 40 may simultaneously close a second relay switch 42 which reverses the drive D to move the ridge 2 out of the recess 10b and to allow for convenient removal of a finished blank.

Each of the signal generators 5 may be replaced by a separate switch whose movable contact may be opened or closed in response to movement of the respective panel 30a or 30b to a predetermined position. The relay 40 may be constructed in such a way that it is deenergized when the panels 30a, 30b engage the signal generators 5 and that such deenergization of the relay causes the punch .1 to terminate its working stroke toward the die 10. If one of the signal generators 5 is replaced by an electric switch, the other signal generator may be omitted, particularly if the machine is to form bent blanks whose panels are minor symmetrical with reference to each other.

The operation of the bending machine shown in FIGS. 1 to 4 is as follows:

FIG. 3 illustrates the last stage of the bending operation. A fresh metallic blank 30 has been placed onto the top face 10a and the drive D has caused the punch 1 to move its ridge 2 into the recess 10b to such an extent that the blank 30 is bent around the ridge 2 (zone 31) and that the panels 30a, 30b are also bent by the deforming portions 11 (zones 32). In other words, a portion of each panel is moved from the respective plane t and actually extends into the corresponding channel 4 to move into bodily contact with one of the signal generators 5.

The deformation in the zone 31 exceeds the elastic limit of the material of the blank 30 so that such deformation remains after the blank is removed from the bending machine. The outer layer of the zone 31 is lengthened or stretched. The deformation in the zones 32 remains within the elastic limits and will disappear when the finished blank is relieved, i.e., when the punch 1 returns to the starting position of FIG. 1.

The relay 40 is energized when the panels 30a, 30b undergo such deformation that the gap between the signal generators 5 is bridged by the blank 30. The relay then opens the switch 41 and the drive D is reversed on simultaneous closing of the switch 42 so that the punch 1 begins to perform a return stroke and moves from the position of FIG. 3 back to the position of FIG. 1. The drive D may comprise a reversible transmission whose gears may be shifted in forward or reverse.

The deformation in the zones 32 disappears when the punch 1 begins to move away from the die 10, and such movement of the punch also relieves stresses in the permanently deformed zone 31.

By properly selecting the position of the stops 3, of the deforming portions 11, and of the signal generators 5, the designer will insure that the blank 30 undergoes a desired degree of deformation. Such deformation is largely independent of minor and even substantial variations in the thickness and/or other characteristics of consecutive blanks 30. Such variations are often ob servable even if several blanks are obtained by subdivision of the same sheet of metallic material. The angle a is substantially constant on each of a series of consecutive blanks.

FIG. 5 illustrates a portion of a modified bending mas chine which includes an air-forming die and a slightly modified punch 101. The configuration of the stops 3 and ridge 2 is the same as shown in FIGS. 1 and 3 but the signal generators 5' constitute movable elements of two valves 50 forming part of a control unit which regulates the operation of a hydraulic or pneumatic drive for the punch 101 and/ or die 10. The signal generators 5' are fully received in the respectivedepressions or channels so that the deforming portions 11 must actually flex the respective panels of the blank 30 before the valves 50 are actuated. The exact construction of the drive which is controlled by the valves 50 and their signal generators 5' forms no part of my present invention.

FIG. 6 shows a portion of a third bending machine wherein the control unit for the drive (not shown) which moves the punch 1 with reference to the die 10 or vice versa comprises two signal generators in the form of photoelectric cells 60. The zones 32 of the deformed blank 30 will extend into the path of light beams of the respective cells whereby the cells generate signals which reverse the drive so that the ridge 2 is retracted from the recess in the die 10. The light beams produced by the cells 60 may extend in parallelism with the ridge 2 and stops 3 and are preferably positioned in such a way that the panels of the blank 30 are flexed by the deforming portions 11 before the operation of the drive is reversed.

A fourth bending machine is shown in FIG. 7. In this embodiment of my invention, the stops 5" on the punch 201 simultaneously constitute two signal generators and are mounted on insulators 6". The channels 4" extend from the opposite sides of the ridge 2 and to the respective stops 5". It is clear that the stops 5" may be replaced with stops in the form of photoelectric cells, hydraulic valves, pneumatic valves or other types of signal generators, depending on the nature of the drive which is controlled thereby.

As stated hereinbefore, the bending machine may include a control unit which comprises a single signal generator. For example, one of the signal generating stops 5" shown in FIG. 7 can be replaced with a stop 3 of the type shown in FIG. 1. Such simplified apparatus is especially practical when the blank is to be deformed into a body consisting of two mirror symmetrical halves.

In order to achieve some flexing of the panels beyond the planes 1 shown in FIG. 7, the stops 5" may be connected in circuit with suitable time lag relays or other known delay devices which insure that the drive for the punch 201 is reversed a certain interval of time following engagement of stops 5" by the panels of the deformed blank.

Referring finally to FIG. 8, there is shown a fifth bending machine which again comprises an air-forming die 10 and a punch 1. This machine is practically identical with the machine of FIGS. 1 to 4 with the sole exception that the control unit CU is dispensed with. Thus, the drive must be adjusted in such a way that the penetration of the ridge 2 into the recess of the die 10 is terminated automatically when the zones 32 of the blank 30 are flexed to a desired degree. The deformation in the Zones 32 will disappear when the punch 1 is retracted from the position of FIG. 8, and the radius of curvature of the rounded peripheral surface on the ridge 2 preferably equals or approximates the thickness of the blank 30. It was found that the machine of FIG. 8 will produce finished blanks with the same angle a between the two mutually inclined panels despite the fact that the thickness and/or certain other characteristics of the starting material might vary within a certain range.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of my contribution to the art.

What is claimed as new and desired to be protected by Letters Patent is:

1. In a sheet metal bending machine, an air-forming die member having a face provided with a recess bounded by a pair of deforming portions; and a punch member having a ridge disposed between said deforming portions and a pair of stops each separated from said ridge by a depression of said punch member, each of said deforming portions being located between said ridge and one of said stops opposite one of said depressions so that, when a blank is placed onto said face and said ridge is caused to penetrate into said recess, the blank is bent around said ridge and forms a pair of panels each of which abuts against one of said deforming portions and against one of said stops whereby the deforming portions effect elastic deformation of said panels and urge portions of the respective panels into corresponding depressions to thus compensate for variations in bending angle caused by differences in characteristics of successively treated blanks.

2. A structure as set forth in claim 1, wherein said stops and said deforming portions are disposed mirror symmetrically with reference to a plane which extends lengthwise of and halves said recess and said ridge.

3. A structure as set forth in claim 1, wherein said ridge is provided with a rounded peripheral surface whose radius of curvature at least approximates the thickness of the blank.

4. A structure as set forth in claim 1, wherein said recess is of triangular cross section and wherein said punch member is reciprocable with reference to said die member.

5. In a sheet metal bending machine, an air-forming die member having -a face provided with a recess bounded by a pair of deforming portions; a punch member having a ridge disposed between said deforming portions and a pair of stops spaced from said ridge, each of said deforming portions being located between said ridge and one of said stops so that, when a blank is placed onto said face and said ridge is caused to penetrate into said recess, the blank is bent around said ridge and forms a pair of panels each of which abuts against one of said deforming portions and against one of said stops; drive means for moving one of said members with reference to the other member to thereby move said ridge into or from said recess; and control means for regulating the operation of said drive means including signal generating means provided on said punch member intermediate one of said stops and said ridge and arranged to produce a signal which terminates the operation of said drive means in a direction to effect movement of said ridge into said recess when the respective panel of the blank assumes a predetermined position with reference to said control means.

6. A structure as set forth in claim 5, wherein said control means comprises two signal generators each of which is disposed between one of said stops and said ridge.

7. A structure as set forth in claim 6, wherein said signal generators are disposed substantially midway between said ridge and the respective stops.

8. A structure as set forth in claim 6, wherein said punch member is provided with a pair of channels each of which extends between said ridge and one of said stops and wherein each of said signal generators is fully received in one of said channels.

9. A structure as set forth in claim 8, wherein said signal generators are positioned in such a way that the operation of said drive means is terminated when the mutual inclination of said panels at least approximates the desired inclination of such panels on the finished blank.

10. A structure as set forth in claim 8, wherein each of said signal generators is slightly offset from a plane which is tangential to said ridge and to the respective stop so that, in order to come in actual contact with a signal generator, the respective panel must be flexed sufficiently to extend into the corresponding channel.

11. A structure as set forth in claim 6, wherein said signal generators constitute the terminals of a normally open electric switch and further comprising insulating means disposed between said punch member and each of said terminals, said switch being closed by the blank when the panels come in actual abutment with the respective terminals.

12. A structure as set forth in claim 6, wherein each of said signal generators comprises a movable member of a fluid flow controlling valve and wherein said drive means is operated by fluid.

13. A structure as set forth in claim 6, wherein each of said signal generators comprises a photoelectric cell.

14. In a sheet metal bending machine, an air-forming die member having a face provided with a recess bounded by a pair of deforming portions; a punch member having a ridge disposed between said deforming portions and a pair of stops spaced from said ridge, each of said deforming portions being located between said ridge and one of said stops so that, when a blank is placed onto said face and said ridge is caused to penetrate into said recess, the blank is bent around said ridge and forms a pair of panels each of which abuts against one of said deforming portions and against one of said stops, and drive means for moving one of said members with reference to the other member to thereby move said ridge into or from said recess, at least one of said stops constituting a signal generator arranged to produce a signal which terminates the operation of said drive means in a direction to effect movement of said ridge into said recess when the respective panel of the blank assumes a predetermined position with reference to said one stop.

15. As a novel article of manufacture, a punch for use in bending machines for sheet metal blanks or the like, comprising a substantially wedge-like section provided with a longitudinally extending ridge and a pair of stops spaced from and located at the opposite sides of said ridge, said section further having a pair of depressions each of which extends between said ridge and one of said stops, at least one of said stops constituting a signal genreator for controlling the drive of the bending machine.

16. As a novel article of manufacture, a punch for use in bending machines for sheet metal blanks or the like, comprising a substantially wedge-shaped section provided with a longitudinally extending ridge and a pair of stops spaced from and located at the opposite sides of said ridge, said section further having a pair of depressions each of which extends between said ridge and one of said stops, and a signal generator accommodated in one of said depressions and arranged to control the operation of the drive of the bending machine.

17. As a novel article of manufacture, a punch for use in bending machines for sheet metal blanks or the like, comprising a substantially wedge-shaped section provided with a longitudinally extending ridge and a pair of stops spaced from and located at the opposite sides of said ridge, said section further having a pair of depressions each of which extends between said ridge and one of said stops, and a pair of signal generators each provided in one of said depressions, said signal generators being arranged to control the operation of the drive for the bending machine.

18. A punch as set forth in claim 17, wherein said signal generators are fully received in the respective depressions.

References Cited UNITED STATES PATENTS 1,535,295 4/1925 Connery 72-413 2,840,135 6/1958 Fowler 72-26 3,181,323 5/1965 Bos 72-26 RONALD D. GREFE, Primary Examiner.

U.S. Cl. X.R. 72-26, 30, 414 

